btrfs: Replace fs_info->readahead_workers workqueue with btrfs_workqueue.

Replace the fs_info->readahead_workers with the newly created
btrfs_workqueue.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Tested-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>

fs/btrfs/ctree.h

@@ -1517,7 +1517,7 @@ struct btrfs_fs_info {
 	struct btrfs_workqueue_struct *endio_freespace_worker;
 	struct btrfs_workqueue_struct *submit_workers;
 	struct btrfs_workqueue_struct *caching_workers;
-	struct btrfs_workers readahead_workers;
+	struct btrfs_workqueue_struct *readahead_workers;
 
 	/*
 	 * fixup workers take dirty pages that didn't properly go through

fs/btrfs/disk-io.c

@@ -2008,7 +2008,7 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
 	btrfs_destroy_workqueue(fs_info->submit_workers);
 	btrfs_stop_workers(&fs_info->delayed_workers);
 	btrfs_destroy_workqueue(fs_info->caching_workers);
-	btrfs_stop_workers(&fs_info->readahead_workers);
+	btrfs_destroy_workqueue(fs_info->readahead_workers);
 	btrfs_destroy_workqueue(fs_info->flush_workers);
 	btrfs_stop_workers(&fs_info->qgroup_rescan_workers);
 }
@@ -2522,14 +2522,11 @@ int open_ctree(struct super_block *sb,
 	btrfs_init_workers(&fs_info->delayed_workers, "delayed-meta",
 			   fs_info->thread_pool_size,
 			   &fs_info->generic_worker);
-	btrfs_init_workers(&fs_info->readahead_workers, "readahead",
-			   fs_info->thread_pool_size,
-			   &fs_info->generic_worker);
+	fs_info->readahead_workers =
+		btrfs_alloc_workqueue("readahead", flags, max_active, 2);
 	btrfs_init_workers(&fs_info->qgroup_rescan_workers, "qgroup-rescan", 1,
 			   &fs_info->generic_worker);
 
-	fs_info->readahead_workers.idle_thresh = 2;
-
 	/*
 	 * btrfs_start_workers can really only fail because of ENOMEM so just
 	 * return -ENOMEM if any of these fail.
@@ -2537,7 +2534,6 @@ int open_ctree(struct super_block *sb,
 	ret = btrfs_start_workers(&fs_info->generic_worker);
 	ret |= btrfs_start_workers(&fs_info->fixup_workers);
 	ret |= btrfs_start_workers(&fs_info->delayed_workers);
-	ret |= btrfs_start_workers(&fs_info->readahead_workers);
 	ret |= btrfs_start_workers(&fs_info->qgroup_rescan_workers);
 	if (ret) {
 		err = -ENOMEM;
@@ -2549,7 +2545,7 @@ int open_ctree(struct super_block *sb,
 	      fs_info->endio_meta_write_workers &&
 	      fs_info->endio_write_workers && fs_info->endio_raid56_workers &&
 	      fs_info->endio_freespace_worker && fs_info->rmw_workers &&
-	      fs_info->caching_workers)) {
+	      fs_info->caching_workers && fs_info->readahead_workers)) {
 		err = -ENOMEM;
 		goto fail_sb_buffer;
 	}

fs/btrfs/reada.c

@@ -91,7 +91,8 @@ struct reada_zone {
 };
 
 struct reada_machine_work {
-	struct btrfs_work	work;
+	struct btrfs_work_struct
+				work;
 	struct btrfs_fs_info	*fs_info;
 };
 
@@ -733,7 +734,7 @@ static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 
 }
 
-static void reada_start_machine_worker(struct btrfs_work *work)
+static void reada_start_machine_worker(struct btrfs_work_struct *work)
 {
 	struct reada_machine_work *rmw;
 	struct btrfs_fs_info *fs_info;
@@ -793,10 +794,10 @@ static void reada_start_machine(struct btrfs_fs_info *fs_info)
 		/* FIXME we cannot handle this properly right now */
 		BUG();
 	}
-	rmw->work.func = reada_start_machine_worker;
+	btrfs_init_work(&rmw->work, reada_start_machine_worker, NULL, NULL);
 	rmw->fs_info = fs_info;
 
-	btrfs_queue_worker(&fs_info->readahead_workers, &rmw->work);
+	btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
 }
 
 #ifdef DEBUG

fs/btrfs/super.c

@@ -1336,7 +1336,7 @@ static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
 	btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
 	btrfs_set_max_workers(&fs_info->delayed_workers, new_pool_size);
-	btrfs_set_max_workers(&fs_info->readahead_workers, new_pool_size);
+	btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
 	btrfs_set_max_workers(&fs_info->scrub_wr_completion_workers,
 			      new_pool_size);
 }